Peculiar type of focal and segmental lupus glomerulitis: glomerulonephritis or vasculitis?

Dissecting the histological features of lupus nephritis highlights new common patterns of injury in class III/IV

OBJECTIVE

The International Society of Nephrology/Renal Pathology Society classification is the gold standard for the characterisation of lupus nephritis (LN) on renal biopsy, with therapeutic repercussions. Its recent revision simplified the current class subdivisions, eliminating the S/G forms of class IV, although data on a possible pathogenetic/clinical value of this subdivision are still contradictory.

METHODS

353 renal biopsies from Belimumab International Study in LN were assessed through central pathology review. Univariate logistic models and a decision tree were performed on 314 adequate biopsies to evaluate the impact of histological features on focal/diffuse classes. Removing class I/II (n=6) and 'pure' class V (n=34), principal component analysis (PCA) and heatmap were used to explore similarities among III, IVS and IVG biopsies either incorporating or not the mixed classes (+V, n=274). Finally, a method aimed at partitioning the cases into k clusters based on their similarity (KMeans), was used to study features from the cohort of 'pure' class III/IVS/IVG cases (n=214) to determine alternative subdivisions based on phenotypic data.

RESULTS

Segmental endocapillary hypercellularity (EH) was prevalent in class III, global EH, wire loops, hyaline thrombi and double contours were hallmarks of class IVG, with IVS cases showing intermediate characteristics. Heatmap and PCA confirmed the segregation of these features among classes, showing better segregation for focal/diffuse LN as compared with the mixed classes (+V). KMeans revealed the presence of two main clusters, membranoproliferative-like (n=83) or vasculitis-like (n=131).

CONCLUSIONS

This study reveals new phenotypic forms of LN surpassing the traditional classes as determined by the current classification. Future validation and confirmation are required to confirm these findings.

Pauci-immune lupus nephritis: possibility or co-incidence?

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized with immune complex formation and renal involvement of lupus and may include several kinds of pathological conditions, but mostly, it is associated with immune complex-induced glomerular disease. Pauci-immune lupus nephritis is a very rare condition. We describe a 45-year-old female patient with pauci-immune crescentic necrotizing lupus nephritis and briefly discuss the possible mechanism and pathogenesis.

Classifying lupus nephritis: an ongoing story

The role of the renal biopsy in lupus nephritis is to provide the diagnosis and to define the parameters of prognostic and therapeutic significance for an effective clinicopathological correlation. Various classification schemas initiated by World Health Organization in 1974 have been proposed until the most recent update by International Society of Nephrology/Renal Pathology Society in 2004. In this paper, we reviewed the new classification system with the associated literature to highlight the benefits and the weak points that emerged so far. The great advantage of the classification emerged to provide a uniform reporting for lupus nephritis all over the world. It has provided more reproducible results from different centers. However, the studies indicated that the presence of glomerular necrotizing lesion was no longer significant to determine the classes of lupus nephritis leading to loss of pathogenetic diversity of the classes. Another weakness of the classification that also emerged in time was the lack of discussions related to the prognostic significance of tubulointerstitial involvement which was not included in the classification. Therefore, the pathogenetic diversity of the classification still needs to be clarified by additional studies, and it needs to be improved by the inclusion of the tubulointerstitial lesions related to prognosis.

Pathological spectrums and renal prognosis of severe lupus patients with rapidly progressive glomerulonephritis

The objectives of the study were to investigate the pathological features and renal prognosis of severe lupus patients with rapidly progressive glomerulonephritis. One hundred and one cases of biopsy-proven severe LN with rapidly progressive glomerulonephritis (RPGN) were analyzed in this retrospective study. Another 200 severe LN patients without RPGN were randomly enrolled as a control group. Their clinicopathological data and long-term outcome were compared. There were 76 females and 25 males with an average age of 31.9 ± 14.2 years followed for a median period of 4 years. Compared with controls, patients with RPGN had shorter LN duration (p = 0.008), higher level of creatinine (p < 0.001), severe anemia (p = 0.037), heavier hematuria (p < 0.001), severe tubular injury parameters [NAG (p < 0.001), RBP (p < 0.001), C3 (p < 0.001)], higher scores of AI (p = 0.001) and CI (p = 0.004), higher proportions of glomerular sclerosis (0.033) and crescents (p < 0.001), severe tubulointerstitial lesions (p < 0.001) and interstitial inflammation (p < 0.001), lower rate of complete remission (33.9 vs 68.2 %) and higher rate of treatment failure (46.8 vs 7.9 %). The 3-, 5- and 10-year cumulative renal survival rates of RPGN and non-RPGN patients were 65.1 versus 53.9 versus 42.9 and 96.9 versus 94.9 versus 91.7 %, respectively. Multivariate analysis revealed that SCr concentration and the proportion of crescents were the most important risk factors for end-stage renal disease (ESRD) in severe LN with RPGN (p < 0.001). In conclusion, RPGN occurred in 3.6 % of LN and is associated with severe renal manifestations, serious sclerotic and crescentic glomeruli lesions, severe tubulointerstitial inflammation, atrophy and fibrosis, prominent leukocyte infiltration and worse treatment response. Multivariate analysis revealed that SCr concentration and the proportion of crescents were the most important risk factors for ESRD. 57.1 % of severe LN patients with RPGN might progress to ESRD within 10 years.

Renal disease in systemic lupus erythematosus with emphasis on classification of lupus glomerulonephritis: advances and implications

CONTEXT

Systemic lupus erythematosus is an autoimmune disease with protean clinical and pathologic manifestations involving almost all organs in the body. There is a high incidence of renal involvement during the course of the disease, with varied renal pathologic lesions and diverse clinical features. A renal biopsy examined by routine light microscopy, immunofluorescence, and electron microscopy contributes toward diagnosis, prognostic information, and appropriate management.

OBJECTIVES

(1) To review the clinical and various pathologic features of renal lesions in systemic lupus erythematosus patients. (2) To introduce the International Society of Nephrology and Renal Pathology Society Classification of Lupus Glomerulonephritis.

DATA SOURCES

A literature review, illustrations with original artwork, and tabulation of clinical and pathologic data of cases obtained from the authors' renal biopsy files examined during the last 8 years were used.

CONCLUSIONS

The International Society of Nephrology/ Renal Pathology Society-sponsored Classification of Lupus Glomerulonephritis proposes standardized definitions of the various pathologic findings, describes clinically relevant lesions, incorporates prognostic parameters, and recommends a uniform way of reporting the renal biopsy findings. Lupus glomerulonephritis is divided into 6 classes primarily based on the morphologic lesions, extent and severity of the involvement, immune complex deposition, and activity and chronicity. Special emphasis is laid on describing qualitative as well as quantitative morphologic data and to include the accompanying tubulointerstitial disease and different vascular lesions, which have prognostic and therapeutic significance. This classification is intended to facilitate a higher degree of reproducibility, resulting in better patient care and more effective future clinical and translational research. Renal biopsy findings in systemic lupus erythematosus add new and independent parameters of prognostic significance to established clinical and genetic factors.

Necrotizing and crescentic lupus nephritis with antineutrophil cytoplasmic antibody seropositivity

BACKGROUND AND OBJECTIVES

Lupus nephritis is a classic immune complex glomerulonephritis. In contrast, antineutrophil cytoplasmic antibodies are associated with necrotizing and crescentic glomerulonephritis, in the absence of significant immune deposits. Antineutrophil cytoplasmic antibodies are detected by indirect immunofluorescence in 20% of patients with systemic lupus erythematosus. We report 10 cases of necrotizing and crescentic lupus nephritis with antineutrophil cytoplasmic antibody seropositivity.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Ten patients with systemic lupus erythematosus, antineutrophil cytoplasmic antibody positivity, and renal biopsy findings of lupus nephritis and antineutrophil cytoplasmic antibody-associated glomerulonephritis were identified. The clinical features, pathologic findings, and outcomes are described.

RESULTS

The cohort consisted of eight women and two men with a mean age of 48.4 yr. Perinuclear antineutrophil cytoplasmic antibody was detected by indirect immunofluorescence in nine patients. Four of the nine patients and the single remaining patient were found to have myeloperoxidase-antineutrophil cytoplasmic antibodies by enzyme-linked immunosorbent assay. Clinical presentation included proteinuria, hematuria, and acute renal insufficiency, with mean creatinine of 7.1 mg/dl. All biopsies exhibited prominent necrosis and crescents with absent or rare subendothelial deposits and were interpreted as lupus nephritis and antineutrophil cytoplasmic antibody-associated glomerulonephritis. All patients received cyclophosphamide and prednisone. Three patients died of infectious complications. Among the remaining seven patients, five achieved a complete or near-complete remission, one had a remission with subsequent relapse, and one had no response to therapy.

CONCLUSION

Antineutrophil cytoplasmic antibody-associated necrotizing and crescentic glomerulonephritis may occur superimposed on lupus nephritis. In patients with lupus nephritis and biopsy findings of prominent necrosis and crescent formation in the absence of significant endocapillary proliferation or subendothelial deposits, antineutrophil cytoplasmic antibody testing by enzyme-linked immunosorbent assay is recommended.

"Pauci-Immune" proliferative and necrotizing glomerulonephritis with thrombotic microangiopathy in patients with systemic lupus erythematosus and lupus-like syndrome

In the glomerulonephritides of systemic lupus erythematosus (SLE), the number of subendothelial deposits, when present, generally corresponds to the degree of light microscopic glomerular hypercellularity; only very rarely are no or few such deposits present in cases of focal (WHO class III) or diffuse (WHO class IV) proliferative lupus nephritis. We have recently encountered five cases of active diffuse proliferative glomerlonephritis with no subendothelial and few or no mesangial deposits and thrombotic microangiopathy (TMA) in four patients with SLE and one patient with lupus-like syndrome. Three of the five patients were tested for circulating lupus anticoagulants or anticardiolipin antibodies, and two were positive. All five patients tested negatively for antineutrophil cytoplasmic antibodies (ANCA). Three patients responded to steroid and cyclophosphamide treatment, although one of them died of acute bacterial bronchopneumonia. One patient was lost to follow-up. We conclude that "pauci-immune" proliferative lupus nephritis is rare and should be treated as proliferative lupus nephritis with a proportionate number of subendothelial deposits. The negative ANCA suggests that these cases do not represent incidental ANCA-associated pauci-immune necrotizing and crescentic glomerulonephritis in patients with SLE. Of particular interest is that, in patients with SLE, if associated with TMA, an active proliferative necrotizing glomerulonephritis may be present even in the absence of significant glomerular immune complex deposition.

Membranous lupus nephritis with antineutrophil cytoplasmic antibody-associated segmental necrotizing and crescentic glomerulonephritis

Focal segmental necrotizing and crescentic lupus nephritis accompanied by perinuclear antineutrophil cytoplasmic antibody (P-ANCA) seropositivity is an unusual occurrence. We report the first biopsy-documented cases of membranous lupus nephritis class V with associated "pauci-immune" segmental necrotizing glomerulonephritis and P-ANCA seropositivity. The absence of subendothelial electron-dense deposits favored a manifestation of superimposed ANCA-associated glomerulonephritis rather than class III lupus nephritis. The pathogenetic implications of this association are explored.